1. Field of the Invention
This invention relates generally to power meters used to measure the power exerted on a bicycle. More particularly, the present invention is a single sided power meter that measures the power exerted on one side of the bicycle and other bicycle operating parameters, and then estimates the total power exerted on the bicycle using the measured single-sided power and the other measured parameters.
2. Discussion of the Related Art
Many individuals desire systems that monitor performance during an exercising session. This is especially true for competitive athletes, who desire a quantifiable measure of their performance. A number of force and power meters are used in conjunction with bicycles. Many of these power meters measure power at a single location, such as at the chain ring or the hub of the driven wheel, or measure the forces applied to both sides of the bicycle individually, such as at the pedals or the crank arms. In these approaches, all of the power/force is measured in the direct load path of the bicycle drivetrain. However, in the latter type of power measurement system, it can be expensive and burdensome to install and calibrate power meters on both sides of the bicycle or to measure total power in the direct load path. As a result, single sided power measurement devices have been developed. Typical single sided power measurement devices measure power applied to one side of the power input system, such as using one of the pedals or one of the crank arms, and then simply by double the power measured on the single side. This gives an estimate of the total power derived from both legs under a symmetric assumption, which assumes that both legs are providing the same amount of power. This method of calculating total power, while relatively low in cost, is oftentimes imprecise in that there can be significant differences in power input from one side to the other. That is because even highly trained bicyclists pedal with at least some amount of asymmetry based on factors such as strength and coordination differences between dominant and non-dominant legs and fatigue characteristics. By using the symmetric assumption, seemingly small errors can be increasingly worsened by a factor of two and potentially provide significant imprecision of the overall estimated power value.
There is thus a need for a single-sided power meter, which is relatively low in cost, which is able to provide a heightened level of accuracy in estimating the input forces applied to the bicycle by the bicyclist.